In the year 1992, the United States Environmental Protection Agency (EPA) and Department of Energy (DOE) launched an Energy Star plan. The Energy Star 4.0 further defines a 80 PLUS specification for power supplies. The 80 PLUS is targeted at ensuring that a conversion efficiency of greater than 80% is provided when a power supply is not in a load level. The 80 PLUS specification, according to conversion efficiencies, can be graded into copper, silver, gold, platinum and titanium. With respect to the platinum grade, it specifies that when a power supply is in half-load and an external power is a 200V input, the conversion efficiency of the power supply needs to maintain at 94% in order to pass verification.
Referring to FIG. 1, a conventional power supply 50 completely lays out a power supply circuit 51 on a same circuit board 52, and a cooling fan 53 for dissipating heat of the circuit board 52 is placed at one end of the power supply 50, as shown in FIG. 1. However, among the modules in the power supply circuit 51, a bridge rectification module 511 has a highest power consumption, which occupies 12.3% of the total power consumption of the power supply 50. A part of the power consumption of the bridge rectification module 511 is generated due to temperature rise caused by operations. Thus, when a designer lays out components of the power supply 50, positions of other elements and the bridge rectification module 511 also need be considered to prevent large-area elements from blocking air currents for dissipating heat of the bridge rectification module 511. For example, a path of an air current is as shown by 54 in FIG. 1. However, the size of the power supply 50 is regulated (e.g., by the Advanced Technology eXtended, ATX, standard) and cannot be modified as desired, adding limitations to the layout of elements such that the power consumption of the bridge rectification module 511 cannot be effectively resolved.